The Leaf as a Living Material: Functional Implications of Morphological Variation in Leaf Photosynthetic Tissue
Date of Award
Spring 2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Forestry and Environmental Studies
First Advisor
Brodersen, Craig
Abstract
Photosynthetic rate is constrained by spatial and temporal fluxes of CO2, light, and H2O within the leaf. The transport processes underlying these fluxes are determined by mechanisms such as mesophyll structure and its physical properties. Yet, given the scale and complexity of leaf internal anatomy, the relative contribution and mechanisms underpinning the role of mesophyll structure in photosynthesis have historically been difficult to test. In the years to come, a deeper understanding of plant carbon assimilation will be critical to meeting the challenges of climate change. Carbon assimilation models can be used to predict the effects of environmental stress on plant growth, to develop crops for better yield or resiliency, and to calculate the drawdown effect of plants on atmospheric CO2. This requires an accurate understanding of the photosynthetic process, which has relied historically on overly simplified anatomical models. Using a combination of spatially resolved 3D image data, physiological measurements, and in silico modeling, my dissertation work aims to improve our fundamental understanding of leaf internal architecture, or mesophyll cell geometry and organization, and how variation in leaf mesophyll structure influences the distribution of light and CO2 inside a leaf, thus acting to promote or constrain C3 carbon assimilation. In Chapter 1, I examine structure-function relationships in the highly productive, upper layer of leaf photosynthetic tissue, the palisade mesophyll. Alternative palisade cell morphologies previously described in the taxon Viburnum provide a model system for investigating the link between tissue morphology, environment, and leaf photosynthetic performance. In Chapter 2, I characterize the structure of the spongy mesophyll, found in the lower leaf. This work reveals the presence of well-conserved structural motifs that obey fundamental physical laws and that are associated with leaf traits such as cell size, stomatal density, and maximum photosynthetic rate. In Chapter 3, I test the mechanistic basis of spongy mesophyll structure on leaf tissue optics and diffusion-reaction dynamics using in silico, finite volume method (FVM) modeling. Taken together, these studies aim to improve our knowledge of leaf mesophyll functional morphology at multiple scales—across land plant diversity and within a model genus, and to advance our understanding broadly of the role of leaf architecture in carbon assimilation.
Recommended Citation
Borsuk, Aleca, "The Leaf as a Living Material: Functional Implications of Morphological Variation in Leaf Photosynthetic Tissue" (2024). Yale Graduate School of Arts and Sciences Dissertations. 1496.
https://elischolar.library.yale.edu/gsas_dissertations/1496
